The two-time Pro Bowl defensive end is to meet with a specialist in North Carolina on Wednesday to have his foot examined, a person familiar with the injury told The Associated Press on Tuesday.
There is concern that Schobel sustained a more serious injury in the mid-foot area, where a cluster of bones forms a small arch between the ankle and toes, known as a Lisfranc injury. It is the type of injury that ended Indianapolis Colts defensive end Dwight Freeney's season last November, the person said.
The person spoke on condition of anonymity because the Bills have not released the nature or severity of the injury.
Depending on what the tests show, Schobel could miss as few as two weeks, the person said. Schobel has already missed three games since aggravating the injury during a 41-17 loss at Arizona on Oct. 5. He was initially hurt a week earlier during a 31-14 win at St. Louis.
"We won't comment on the specifics of a player's injury," Bills spokesman Scott Berchtold said in an e-mail to the AP.
The Bills (5-3) return to practice Wednesday to prepare to play at New England this weekend.
On Monday, coach Dick Jauron suggested Schobel had hit a setback in his recovery by listing the player as week-to-week. Jauron previously had not provided a timetable except to express hope that Schobel would resume practicing soon.
Schobel's injury is the latest setback for a Bills defense that is now without its top defensive back, safety Donte Whitner, who's out indefinitely after separating his right shoulder in a 26-17 loss to the New York Jets last weekend.
The decision to have Schobel's foot re-examined came after the player took part in individual running drills during practice last week. Schobel had previously been limited to watching practice while wearing a protective boot.
The Bills' pass rush has dwindled since Schobel was hurt. After registering 10 sacks in opening the season with four victories, Buffalo has managed just three in going 1-3 in its past four games.
The inability to pressure quarterbacks has also put a dent into the Bills' pass defense. Opposing quarterbacks have gone a combined 96-of-129 for 973 yards with five touchdowns and two interceptions in the past four games.
Schobel managed just one sack before he was hurt but had been among the team leaders with 32 tackles. Selected by Buffalo in the second round of the 2001 draft, Schobel ranks second on the team with 68 career sacks.